Enhance your triangles and oblongs by embracing arches and curves

Crafting the old fashioned way

African designers and engineers are reluctant to shift from traditional brick, cement and concrete materials to mass timber; however, a select group of South African innovators are embracing it and curved timber.

Nature provides compelling examples of curved structures; for instance, the spiral shape of snail shells and the curvature of sea anemone shells are fragile yet exceptionally strong in their environments.

Curved structures in mass timber exhibit enhanced strength, versatility, and aesthetic appeal. As mass timber gains significant traction globally, the emphasis is increasingly placed on superior engineering, advanced glue-laminated timber, cross-laminated timber (CLT) and its big brother, mass timber.

Moreover, when considering a steel I-beam, its load-bearing capacity is determined by the weight of the steel in relation to the beam's dimensions.

WHY USE CURVES?

Arched doorways constructed from stone or brick are much stronger than those with flat lintels. This principle holds true across various applications in construction and nature, where curves consistently outperform flat designs in terms of strength and visual appeal.

Their graceful lines enhance the visual interest of otherwise mundane buildings.

The primary barrier is the lack of skill to construct true arches and curves, regardless of the materials employed. This expertise, including assessing and calculating stress loads before curved construction, is not adequately taught in most construction-related professions.

While almost anything can be designed using modern software, who will build it?

Top image: Shaping the laminated horn | Above image: Assembling the canopy and horn

Achieving curves in timber presents a greater challenge compared to traditional building materials. While curved wood has been utilised for centuries, modern engineering and adhesive technologies enable the creation of structural curves in two-dimensional (2D) and three-dimensional (3D) forms.

Only a select few produce 3D curved glue-laminated beams, as precision is paramount. These beams are crafted using traditional methods and are tailored specifically to meet the requirements of individual projects.

CLT traces its origins to the first patents filed in France in 1985, with significant advancements made by Gerhard Schickofer in his 1994 PhD thesis in Austria. Today, CLT represents a remarkable blend of skill, engineering, and innovation, rapidly becoming the preferred method for mass timber construction for various reasons.

FREE FORMING

This design allows the column to support up to 5,000 kg of weight, effectively distributing the load evenly across all curved columns.

The significance of adhesives and fasteners cannot be overstated, as they contribute substantially to the strength of this structural system, which has demonstrated considerable success.

Currently under construction is a timber canopy anticipated to weigh around 4.5 metric tonnes, measuring 19.5m in length and 8.5m wide. The design features a hybrid glue-laminated and cross-laminated timber ring beam that unifies the entire canopy, supported by two structural horns standing 6.35m tall to balance and support most of the canopy's weight.

The structure relies on the structural horn and two additional concealed support columns. Notably, 45% of the canopy is designed to 'float' freely, allowing for slight flexing in response to high mountain winds, similar to how a yacht's mast bends in the breeze. This flexibility mitigates excessive stress on the structure, thereby enhancing its durability.

A view from the top in Addo Eco Park

Globally, timber is recognised as the sustainable building material of the future. While its application across various construction sectors is rapidly expanding, we must continue investigating engineering advancements and developing new mass and glue-laminated timber construction techniques and share them openly with those aspiring to create superior structures.

Nature-following free form timber is at home in Addo Eco Park

Source: Woodbiz Africa / SA Forestry - September 2024 Newsletter (Pages 35 - 38)